tcp: add tcpi_bytes_acked to tcp_info

This patch tracks total number of bytes acked for a TCP socket.
This is the sum of all changes done to tp->snd_una, and allows
for precise tracking of delivered data.

RFC4898 named this : tcpEStatsAppHCThruOctetsAcked

This is a 64bit field, and can be fetched both from TCP_INFO
getsockopt() if one has a handle on a TCP socket, or from inet_diag
netlink facility (iproute2/ss patch will follow)

Note that tp->bytes_acked was placed near tp->snd_una for
best data locality and minimal performance impact.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Cc: Matt Mathis <mattmathis@google.com>
Cc: Eric Salo <salo@google.com>
Cc: Martin Lau <kafai@fb.com>
Cc: Chris Rapier <rapier@psc.edu>
Signed-off-by: David S. Miller <davem@davemloft.net>

3 files changed, 6 insertions, 1 deletions

diff --git a/include/linux/tcp.h b/include/linux/tcp.h
index 0caa3a2d4106..0f73b43171da 100644
--- a/include/linux/tcp.h
+++ b/include/linux/tcp.h
@@ -150,6 +150,10 @@ struct tcp_sock {
         u32     rcv_wup;        /* rcv_nxt on last window update sent   */
         u32     snd_nxt;        /* Next sequence we send                */
 
+        u64     bytes_acked;    /* RFC4898 tcpEStatsAppHCThruOctetsAcked
+                                 * sum(delta(snd_una)), or how many bytes
+                                 * were acked.
+                                 */
         u32     snd_una;        /* First byte we want an ack for        */
         u32     snd_sml;        /* Last byte of the most recently transmitted small packet */
         u32     rcv_tstamp;     /* timestamp of last received ACK (for keepalives) */
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 051dc5c2802d..dd7b4ea6a10c 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -576,7 +576,7 @@ static inline int tcp_bound_to_half_wnd(struct tcp_sock *tp, int pktsize)
 }
 
 /* tcp.c */
-void tcp_get_info(const struct sock *, struct tcp_info *);
+void tcp_get_info(struct sock *, struct tcp_info *);
 
 /* Read 'sendfile()'-style from a TCP socket */
 typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
diff --git a/include/uapi/linux/tcp.h b/include/uapi/linux/tcp.h
index 3b9718328d8b..6666e98a0af9 100644
--- a/include/uapi/linux/tcp.h
+++ b/include/uapi/linux/tcp.h
@@ -189,6 +189,7 @@ struct tcp_info {
 
         __u64   tcpi_pacing_rate;
         __u64   tcpi_max_pacing_rate;
+        __u64   tcpi_bytes_acked; /* RFC4898 tcpEStatsAppHCThruOctetsAcked */
 };
 
 /* for TCP_MD5SIG socket option */